As limited as are the studies regarding peritoneal Natural Orifice Trans-Luminal Endoscopic Surgery, mediastinal transluminal experiments are certainly in their infancy. The authors evaluate the parallel development of minimally invasive thoracic surgery with regard to its counterpart in peritoneal laparoscopy to NOTES. Transesophageal interventions by both endosonographic and direct visualization are examined in the context of minimally invasive surgery and mediastinal NOTES. Techniques of viscerotomy creation, visualization, and closure are examined with particular emphasis on mediastinal structures. The state of current interventions is examined. Finally, current morbidity (including infectious complications) and survival outcomes are examined in those animals that have undergone transesophageal exploration.
Surgical section of the abdominal wall has been the traditional access to the abdominal cavity and is commonly referred to as open abdominal surgery or laparotomy. Many of the complications of laparotomy that are related to incision of the abdominal wall include incisional pain and extended convalescence, with wound infections occurring in 2% to 25% and incisional hernias in 4% to 18% of patients undergoing laparotomy in the United States. The development of laparoscopic surgery has led to smaller incisions, which in turn has led to a marked reduction in incision-related complications. Additionally, a trend toward faster recovery, decreased wound-related infections, and a reduction in postoperative pain have been noted in clinical trials comparing laparoscopic to open procedures. Such findings being noted, laparoscopic surgery carries particular risks beyond those of conventional surgery. Procedural complications arise owing to problems with maneuverability and visualization, and the lack of tactile feedback in a 2-dimensional visual field imposes limitations not manifest in classic open procedures. Complications arise from injuries to vascular structures via needles and trochars; carbon dioxide gas emboli can occur from the creation of a pneumoperitoneum. Injury rates up to three times that of laparotomy had, at one time, been reported. Although the rates of complications have been reduced over recent years, this history should be kept in mind as we embark again upon new surgical procedures.
Natural orifice transluminal endoscopic surgery (NOTES) is part of the spectrum of evolving surgical concepts. The idea of endoscopic manipulations taking place outside the gastrointestinal lumen was validated with the success of procedures such as the endoscopic transgastric pseudocyst drainage, or the transesophageal management of mediastinal abscesses. Reports such as the complete removal of a necrotic spleen by transgastric debridement, as well as pancreatic necrosectomy, give weight to therapeutic endoscopic endeavors proceeding beyond simple biopsies and aspirates. Additionally, the surprisingly low incidence of complications after accidental puncture with immediate closure of the gastric wall with endoscopic tumor removal or large colonic polypectomies supported the resolve of endoscopic researchers to perform endoscopic surgery via a natural orifice.
NOTES involves the insertion of flexible endoscopes through natural orifices such as the mouth, rectum, or vagina, with the subsequent incision and penetration of the lumen to gain access to surrounding structures. There are hypothetical benefits of NOTES over conventional open and laparoscopic surgery. The absence of a surface incision eliminates cutaneous scarring and infection ; anesthesia and analgesia requirements can be decreased along with a reduction in recovery time, and hernia and adhesions formation. Morbidly obese patients may undergo intra-abdominal surgeries that were previously inadvisable by cutaneous incision. Finally, economically impoverished countries, where traditional surgical access may be limited and untenable, may now have a viable option for operative care (C. Smith, personal communication, 2008).
As with the introduction of laparoscopic surgery, issues of visualization, orientation, access, and manipulation still need to be addressed before NOTES surgery can be feasible. A number of intra-abdominal NOTES studies have been undertaken to evaluate models, techniques, outcomes, and clinical applicability. A recent review examined 34 intra-abdominal NOTES experimental studies. Of these, 30 were animal based, thus limiting evidence-based interpretations. Of the four human clinical studies, only two represent a series. Hazey and colleagues’ study was a comparison between NOTES peritoneoscopy with diagnostic laparoscopy in 10 patients with a pancreatic mass. Peritoneal access was obtained via an anterior transgastric approach with a mean exploration time of 24 minutes (compared with 13 minutes for laparoscopic evaluation). The decision to proceed with open exploration was consistent for both in 90% (9 of 10 cases); however, in comparison with laparoscopic, 40% visualization of the right lobe of the liver and right upper quadrant structures was inadequate using NOTES. Tsin and colleagues’ study was a case series of 100 patients using a hybrid of mini-laparoscopic–assisted natural orifice surgery for benign surgical conditions. Finally, with animal studies, although intra-abdominal access could be achieved, the best route and method still has not been established. Site closure could not be achieved in all cases and risk of peritoneal infection could not be adequately minimized.
As limited as are the studies regarding peritoneal NOTES, mediastinal transluminal experiments are certainly in their infancy. We evaluate, in this review, the parallel development of minimally invasive thoracic surgery with regard to its counterpart in peritoneal laparoscopy to NOTES. Transesophageal interventions by both endosonographic and direct visualization are examined in the context of minimally invasive surgery and mediastinal NOTES. Techniques of viscerotomy creation (ie, formation of access routes), visualization, and closure are examined with particular emphasis on mediastinal structures. The state of current interventions is examined. Finally, current morbidity (including infectious complications) and survival outcomes are examined in those animals that have undergone transesophageal exploration.
Minimally invasive chest surgery
In 1866, The Dublin Journal of Medical Science published a report entitled “Most extensive pleuritic effusion rapidly becoming purulent, paracentesis, introduction of a drainage tube, recovery, examination of interior of pleura by the endoscope.” The article reported the use of a “new endoscope” developed by a Dr. Francis Richard Cruise in which he performed a thoracoscopy on an 11-year-old girl with an infected pleural cavity.
There have evolved, since the first published reports in the nineteenth century, techniques to visualize the mediastinum that coincide with laparoscopic technological innovation. Mediastinoscopy is a minimally invasive procedure that allows visualization of thoracic lymph node stations 2, 3, 4, 7, and 10 in the staging of lung cancers. To visualize stations 5 and 6, thoracic surgeons use an anterior mediastinotomy (Chamberlain procedure) to access these nodes. Over the past decade, video mediastinoscopy has progressed to allow for much better visualization of the mediastinum to facilitate lymph node sampling. In experienced hands, video mediastinoscopy provides better visualization of the mediastinum, allowing the surgeon to visualize structures that are normally not seen, such as the recurrent laryngeal nerves and the esophagus.
Video-assisted thoracoscopic surgery (VATS) has demonstrable advantages over the traditional thoracotomy, particularly for lung cancer. VATS allows for a small, muscle-sparing incision that allows for visualization of the thorax without spreading the ribs. First described in the early 1990s as a technique in the resection of lung cancer, the literature has shown significant short-term advantages of VATS lobectomy, with recent findings demonstrating long-term oncologic outcomes for VATS similar to traditional open resections. Perioperative mortality rates are low, between 0.5% and 2.7% with low conversion rates in the largest series. The most common complications of arrhythmias, pneumonia, air leak, and myocardial infarction are similar to those reported in the open literature. Short-term outcomes after VATS lobectomy include, as in laparoscopic surgery, low operative blood loss, less postoperative pain, and a quicker return to baseline function. Additionally, 12 months after surgery, none of the patients in Sugiura and colleagues study who had undergone VATS lobectomy complained of post-thoracotomy pain, whereas 26.7% of those undergoing traditional thoracotomy were still taking narcotics for chest pain. Key, however, are the long-term oncologic outcomes. Onaitis and colleagues in a cohort of 500 patients demonstrated a 2-year survival rate for stage 1 and stage 2 disease of 85% and 77%. A randomized trial of 100 patients with 1A lung cancer demonstrated no significant difference in 3- and 5-year overall survival rates between the two groups.
In 1994 a report by McAnena and colleagues described a thoracoscopic-assisted mobilization combined with an open abdominal approach for esophageal resection. A year later, DePaula and colleagues demonstrated the feasibility of laparoscopic transhiatal esophagectomy. From thence, there have been a myriad of minimally invasive esophagectomy (MIE) approaches, which include thoracoscopic-assisted esophageal resection and combined thoracoscopic-laparoscopic resection. Regardless of the approach, safety and feasibility of minimally invasive esophagectomy are equivalent to traditional open approaches. Nguyen and colleagues demonstrated, using a combined thoracoscopic-laparoscopic approach, a mortality (4.3%), major complication (17.4%), and anastomotic leak (8.7%) equivalent to historic controls. Luketich and colleagues have reported the largest series to date of MIE. Again, using a combined approach, 222 patients demonstrated 30-day mortality and anastomotic leak rates similar to historical series with a mean hospital stay of 7 days, much less than seen in open series. Regarding the oncologic adequacy of MIE, several case series suggest outcomes that are comparable with open. Braghetto and colleagues reported a consecutive series of 166 patients undergoing MIE for esophageal cancer. Three-year survival rates were 93.8% for stage 1 disease and 54% for stage 2a disease; there was no significant difference when compared with the open group.
Thus, current data support the use of thoracoscopic techniques with improved short-term outcomes related to a decrease in postoperative pain, less blood loss, and shorter length hospital stay. Studies have demonstrated an immunologic benefit with VATS, resulting in decreased cytokine release and improved lymphocyte function, and there is a return to preoperative function that is related to the avoidance of rib-spreading thoracotomy. However, transesophageal mediastinoscopy and thoracoscopy could eliminate chest wall trauma, for even with a small incision, pain and a relatively extended hospital stay are significant.